I am working with a machinist on getting the spindle bushings reamed. He is checking the tolerances on the 4" dropped axle and wanted to verify the tolerances between the axle and the kingpin. Right now when he measures the size of the kingpin is .812 and the hole in the axle is .825. Do you know what the reasonable tolerance between the two should be? Craig
.013 is probably close enough. The king pin does get pinched when the pinch bolt is installed. You are aware that the king pin does not turn in the axle the spindles turn on the kingpin, correct?
yes I am aware that the kingpin does not move and I am fine with the tolerances but my machinist friend is freaking out right now.
Machinist? ............I am a little surprised you did not buy the reamer or borrow one from a model A friend to do the job on the bushings yourself.....
my bad. He is a good friend and I do not know anyone that has a reamer locally. It started simple and now he is getting a little too picky.
He's not talking about the fit of the pins in the bushings (which is what you ream in normal service). He's talking about the fit of the pin in the axle which is not a normally serviced item. It can be easily fixed when necessary however.This one will probably be O.K. when the lockpin is tighten.
Yeah, I've allways "JackOff" the axle with a rolled up piece of sandpaper. It worked several times for me.
what? the the bore of the king pin hole in the axle is .825? that's not right....the kingpin should barley slide in with slight pressure
Thats pretty sloppy. When repairing truck i-beams i usually aim for .0005-.001" clearance max for a light hammer fit. Posted from the TJJ App for iPhone & iPad
If its a forging This is how I fix them but im sure your anal machinist will disagree http://www.jalopyjournal.com/forum/showthread.php?t=677274
I was just talking to a guy about this the other day on an off topic truck. He had to have the axle sleeved and bored because he felt it was to sloppy. Hes a machinist also haha. I dont know how much is too much but you figure any amount is going to let the kingpin "wiggle" in the axle even with the bolt in it.
I've never measured a real Ford one, and there's no spec in the book...but that sure sounds extra sloppy. Find a local HAMBER with some parts stashed and try a kingpin for wiggle in a couple of Ford axles and/or really measure one. It's a slip fit, but not sloppy. Anyone out there have a Ford made axle and measuring implements close to the computer right now??
I gave up reaming years ago and now have someone with a Sunnen pin hone fit the bushings. Much more life gotten from the bushings that way and no chatter marks ever.
Most old Ford axles are worn as most 70 year old people are. I measured a couple I have laying around and they measure .818 & .820. I make the hole so it is a slight press fit in the bushings and have never had any problems. We have a place in LA that will repair and axle bare hole and they leave a maximum of .003-5 tolerance.
i deleted my post about the spindle bushings tolerances as i re read you question and realized thats not what you were asking the tolerance between the axle and the kingpin needs to be tight, personally i think .013 is too far on the loose side, you should not be able to feel any slack or movement what so ever. its been said by a couple guys here i would think .001 or maybe .0015 on the outside
Here is a way to answer your machinists worries. Clean the bore of the axle and stick a new king pin thru the bore. Insert the kin pin lock and tighten it up tight. Now attempt to wiggle the king pin to the lateral axis and again to the horizontal axis. If the king pin wiggles its too loose and needs attention. If it doesnt wiggle its ok.
You know if you want to tighten these up without doing much work or pulling the axle out. Drill and tap the axle end / kingpin boss area for some set screws. I think it was Kevin Lee that did it with success / came up with it
how about rolling up some pieces of .005" shim stock and slide them in above and under the lock pin ?
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